This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The enzymes RebC and StaC share a common substrate and 67% homology, yet make different products along separate natural product biosynthetic pathways;RebC and StaC are involved in rebeccamycin and staurosporine biosynthesis, respectively. Their reactivities seem to be regulated by the enzymes'FAD binding affinities. Mutation of key residues in RebC has resulted in a "StaC-like" enzyme in both activity and FAD binding, and we now seek to obtain a crystal structure that might explain these changes.